Inlets for aircraft nacelles, wing leading edges, horizontal stabilizers, vertical fins, and other aircraft components may be subject to ice build-up during flight. A heat source may heat the components to prevent the ice build-up or to remove ice after it has built up. The heat source most commonly used today is hot bleed air from a gas turbine engine that heats the backside of the external surface subject to ice build-up. Electric resistance heating has also been proposed and is entering service in a small number of applications.
The material and design of the heated surface and associated structure is typically designed to withstand the possibility of the maximum temperature (which is usually heavy aircraft take-off on a hot, dry ambient day at sea-level, even though this condition may occur infrequently. This condition often drives the design of the heated components, resulting in heavier structures to withstand thermal expansion and/or more expensive materials resistant to the heat.
To achieve efficient electric ice protection, it may be desirable to install heater elements close to the external surface. However, if such elements get damaged or broken, it may be difficult to repair the elements without removing the aircraft or engine from service.